Residents from Mercer and Hunterdon counties could see a 30-inch wide natural gas pipeline run a few dozen miles through local towns if a proposal from a Pennsylvania company is approved by federal regulators.

PennEast Pipeline Co. LLC announced its plans for the pipeline today and received almost immediate opposition from the New Jersey branch of the Sierra Club.

The preliminary proposal indicates that the pipeline would travel from the Marcellus Shale near Wilkes-Barre, Pa., and through four counties in Pennsylvania before crossing the Delaware River and running through western Hunterdon County and into the Hopewell Valley area of Mercer County. Officials from the company said repeatedly that this path could change.

Patricia Kornick, a PennEast spokeswoman, said that the pipeline will bring customers in New Jersey lower, more stable natural gas prices.

“Pipeline companies don’t want to be in residential areas any more than people want them in residential areas,” Kornick said.

The benefits of having the pipeline, however, will outweigh the effects of building it, Kornick said.

“The pipeline itself is going to cut an ugly scar through the land,” said Jeff Tittel, director of the New Jersey branch of the Sierra Club.

Tittel said the pipeline will hurt the environment by promoting fracking in Pennsylvania, promoting the use of fossil fuels and discouraging the transition to renewable energies.

Tittel was also critical of the proliferation of natural gas pipelines in the state.

“Why do we need another one?” Tittel asked.

The PennEast line will run parallel to the Williams Transcontinental pipeline cutting through nearby Montgomery and Princeton. That line is currently in the federal approval process, he said.

PennEast will engage with the community during the federal approval process, which it will begin this fall, Kornick said. During this time, the company welcomes input from residents and municipalities that may be affected.

“It’s critical to the process and effectiveness and success of any project that we be able to engage with community,” Kornick said.

The pipeline is currently in the proposal stage and any eventual version of it could change.

“PennEast understands that there are members of the community that are concerned about the environment,” Kornick said. “PennEast is concerned about the environment.”